HNCYCLOPHDIA OF GARDENING. 
perennials. Double potentillas are hybrids between P. insignia & 
P. argyrophylla atrosanguinea. 
CULTURE: Soil, ordinary deep rich sandy. Position, sunny 
rockeries for dwarf species (P. alba, P. alpestris, P. ambigua, P. cala- 
bria, P. nitida, & P. pyrenaica); sunny borders for tall kinds (P. 
argyrophylla atrosanguinea & vars., P. fruticosa, etc.). Plant, Oct., 
Nov., March or April. Mulch tall kinds with decayed manure aunually 
in-March. Water copiously in dry weather. Apply stimulants occa- 
sionally during flowering period. ‘Lift, divide, & replant border kinds 
in fresh soil every three or four years. Propagate by seeds sown 1-16 in. 
deep, in shallow pans or boxes of light sandy soil in temp. 55° to 65°, 
March, transplanting seedlings outdoors in May or June; or similar 
depth in partially-shaded border outdoors in April; division of roots, 
Oct., Nov., March or April. 
SPECIES CULTIVATED: P. alba, white, spring, 6 in., Europe; alchemellioides, 
white, summer, 6 in., Pyrenees; ambigua, yellow, summer, 6 in., Himalayas; 
argyrophylla, yellow, summer, 2 to 3 ft., Eliwalayas; argyrophylla atrosanguinea, 
crimson; fruticosa, yellow, summer, 3 to 4 tt., Britain; hopwoodiana, yellow and 
rose, summer, 18 in., hybrid; nepalensis, cs:mson, summer, 18 in., Himalayas; 
nitida, rose, summer, 6 in.; Europe; nitida alba, white; nitida grandiflora, pink; 
nitida atrorubens, rose; nitida rosea, rose. Many beautiful hybrids for which 
see trade lists. 
-Poterium (Burnet). — Ord. Rosacee. Hardy perennial herb. 
Leaves used for flavouring soups, salads, & wines. 
CULTURE: Soil, ordinary light. Position, sunny dryish bed or 
border. Plant, 6in. apart in rows Sin. asunder, Feb. Water freely 
in dry weather. Remove flower stems directly they appear. Roots 
to be lifted & replanted annually. Propagate by seeds sown 4 in. deep 
in drills 8in. apart, March, April, or Sept., thinning seedlings when 
2in. high, 6in. apart. 
SPECIES CULTIVATED: P. officinalis (Syn. Sanguisorba officinale), green and 
purple, summer, 2 ft., Europe (Britain). 
Pothos.—Ord. Aroidex. Stove evergreen climbing shrubs. Orn. 
foliage. First introduced 1821. Leaves, roundish or lance-shaped, 
green, or variegated with creamy yellow. 
CULTURE: Compost, equal parts rough peat, sphagnum moss, char- 
coal, & coarse sand. Position, pots with shoots trained to old tree 
stems, trunks of tree ferns or walls. Pot, Feb. or March. Water 
copiously, March to Oct., moderately afterwards. Syringe freely all 
the year round. Temp., Sept. to March, 60° to 65°; March to Sept., 
80° to 85°. Shade from sun essential. Propagate by division of roots, 
Feb. or March. 
SPECIES CULTIVATED: P. argenteus, leaves silvery grey, Borneo; aureus, 
leaves variegated with yellow, Borneo; celatocaulis, stems clinging, Borneo; 
scandens, stems climbing, India. 
Pot Marigold (Calendula officinalis)—See Calendula. 
Pot Marjoram (Origanum Onites)—See Origanum. 
Prairie Rose (Rosa setigera).—See Rosa. 
Prairie Sun-flower (Helianthus rigidus)—See Helianthus. 
Pratia. — Ord. Campanulacee. Hardy herbaceous perennial 
trailing plants. First introduced 1879. ; 
OUTDOOR CULTURE: Soil, two parts peat, one part leaf-mould & 
little sand. Position, sunny well-drained rockeries. Plant, March or 
April. Water freely in dry weather. 
POT CULTURE: Compost, two parts sandy loam, half a part each 
leaf-mould & silver sand. Pot, March. Positior, cool or cold green- 
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